1. Field of the Invention
The present invention relates to a laminated tile or a laminated sheet which exhibits excellent dimensional stability, abrasion resistance and application ability in site and can be suitably used for indoor and outdoor flooring, wall covering and road paving.
2. Description of the Related Art
Generally, floor-covering materials include wood-based, stone-based, fiber-based, resin-based, and rubber-based materials are selectively used depending on property, function and use. Among them, resin-based flooring materials are widely used because of their high mass-productivity.
Typical examples of resin-based flooring materials are a vinyl chloride resin and a urethane-based resin.
The vinyl chloride resin is used in wide applications such as flooring of residences, shops, public services and other broad range of uses because it is inexpensive and has excellent ability in procession and design application. However, as compared with wood-based or stone-based materials, the vinyl chloride resin has a large linear expansion coefficient and contains a large amount of plasticizer, and therefore is inferior in dimensional stability with time after application. Particularly, when the vinyl chloride resin is formed in a tile shape and applied, the tiles made of vinyl chloride resin greatly swell on account of a large coefficient of linear thermal expansion and causes knockout joint area or peeling of the tiles when the tiles are directly heated. Conversely, at extremely low temperatures, the tiles will contract to form gaps in joints.
The urethane-based resin, on the other hand, excellent in impact resistance, abrasion resistance, thermal resistance, chemical resistance, waterproof property and the like, as compared with the vinyl chloride resin. For this reason, the urethane-based resin is used particularly when durability and waterproof property are required, such as veranda, corridors, floors and roofs of factories and public services and other object, and has given actual results as a highly functional flooring material. However, when the urethane-based resin is used as a flooring material, some problems remain unsolved in application ability, i.e., time-consuming coating of the urethane raw material, the long time required for the urethane raw material to cure, i.e., a long curing time, etc., because a field coating method is prevalent, which involves coating or spraying a liquid urethane raw material on substrates in the application site.
On the other hand, a quick curing type urethane raw material, when used, accompanies exothermic heat in the application period. Thus, after curing, volume shrinkage due to hardening of urethane raw materials overlaps volume shrinkage accompanied by temperature reduction. As a result, even though adhesion of the substrate is enough and no peeling is observed in the application period, peeling force acts latently and thus becomes possible, when markedly great external force is applied or when adhesive force is decreased after a long passage of time. In other words, when the urethane-based resin is used as a flooring material, an attempt to improve the application ability would leave anxiety to the dimensional stability and peeling after application.
Then, the present inventors have proposed a laminated product characterized by laminating a urethane-based resin layer on a fiber reinforced resin layer, wherein the fiber reinforced resin layer is obtained by laminating two or more prepreg sheets so as to intersect fiber directions at right angles or obtained by further laminating a nonwoven fabric on one or both surface of the resulting laminating prepreg, and the prepreg sheet is obtained by arranging a continuous reinforcing fiber to one direction and impregnating the arranged fiber with thermoplastic resin so as to make a volume ratio of the reinforcing fiber 50% (see Laid-open Japanese Patent Application No. 192671/99).
This proposed laminated product is excellent in dimensional stability and suitable for use as a flooring material while maintaining the characteristics of the urethane-based resin, i.e., abrasion resistance, impact resistance and the like. In addition, even using the urethane-based resin, this laminated product can be applied without relying on the field coating method, so that the application time can be largely reduced.
Though the foregoing conventional laminated product excels in performance and application ability, there is room for further improvements in the following aspects.
{circle around (1)} Stain is more likely to attach on the surface of softer urethane-based resin. Therefore, wax is generally coated on the surface of urethane-based resin for preventing stain from attaching thereon. However, since the wax is easily removed by friction and the like and poor in durability, the wax must be periodically coated again in order to maintain the effect of the wax.
{circle around (2)} For giving a cushion effect, urethane-based elastomer may be used, among other urethane-based resins, as a flooring material. Though having the chemical resistance equal to or higher than vinyl chloride resin, the urethane-based elastomer is vulnerable to particular organic solvents. Therefore, if the urethane-based elastomer is exposed to a particular organic solvent for a long time, the urethane-based elastomer may expand to cause swelling and warping of a laminated product as the case may be.
{circle around (3)} It is difficult to apply a pattern on a urethane-based resin by printing or the like. Therefore, a colorful laminated product having a high designability is difficult to fabricate.
{circle around (4)} When a urethane-based resin is used as a flooring material, its elasticity can provide walk feeling with a cushion effect. However, with a conventional laminated product, urethane-based resin layers must be provided on both sides of a fiber reinforced resin layer for improving the cushion effect.
The primary object of the present invention is to provide a laminated product which is insusceptible to stain attached thereon even without periodic maintenance, and exhibits improved abrasion resistance and chemical resistance, while excelling in dimensional stability and application ability.
Another object of the present invention is to provide a highly designable laminated product on which an arbitrary pattern can be applied, in addition to the foregoing first object.
A further object of the present invention is to provide a laminated product which is capable of giving a sufficient cushion effect by applying a layer for giving cushion only on one side of a fiber reinforced resin layer, in addition to the foregoing first object.
In view of the above-mentioned problems, the present inventors ended up completing the present invention, as a result of diligent investigations repeatedly made on the problems, by laminating an elastic layer on a fiber reinforced resin layer and a surface protection layer further on the elastic layer.
Specifically, a laminated product according to the present invention has a fiber reinforced resin layer, an elastic layer laminated on one surface of the fiber reinforced resin layer, and a surface protection layer laminated on a surface of the elastic layer for protecting the surface of the elastic layer. The fiber reinforced resin layer includes at least two prepreg sheets, each of which is formed by impregnating a thermoplastic resin into continuous reinforcing fibers arrayed in one direction such that a volume ratio of the continuous reinforcing fibers is in a range of 40 to 80%. The prepreg sheets are laminated so as to directions of the continuous reinforcing fibers at right angles.
According to the present invention, by laminating the fiber reinforced resin layer and elastic layer, the fiber reinforced resin layer restricts large expansion and shrinkage of the elastic layer, while the laminated product has a desired elasticity, so that the dimensional stability is maintained during application and after application. Also, during application, the laminated product may simply be adhered on a substrate without requirements for curing and the like, thereby largely reducing application time. Further, since the surface protection layer is laminated on the surface of the elastic layer, the resulting laminated product is insusceptible to the attachment of stain on the surface thereof and excellent in abrasion resistance and chemical resistance, even if the elastic layer is made of an arbitrary material. It is therefore possible to use the laminated product of the present invention suitably for floors, indoor and outdoor walls, road surfaces, and the like.
Also, a colorful laminated product excellent in designability can be provided by using a transparent surface protection layer, and applying a pattern on the surface of the elastic layer on which the surface protection layer is laminated, or by using a transparent surface protection layer and elastic layer and applying a pattern on the surface of the fiber reinforced resin layer on which the elastic layer is laminated. In this event, the surface protection layer is preferably comprised of a film made of a polyamide resin. Similarly, a colorful laminated product can be provided by making up the surface protection layer of a transparent film and a print layer applied on one side of the film, and laminating the print layer on the elastic layer. Likewise, in this event, the film is preferably made of a polyamide resin.
On the other hand, since the surface protection layer is laminated on the surface of the elastic layer, a variety of materials can be used for the elastic layer, such as thermoplastic resins, thermosetting resins, expanded resins and the like. Among these materials, preferred as a material for the elastic layer is a urethane-based resin. Particularly, when the laminated product is used as a flooring material, the bending modulus is preferably equal to or less than 300 Mpa for providing proper walk feeling.
A second elastic layer may be laminated on the surface of the fiber reinforced resin layer opposite to the surface on which the elastic layer is laminated. The second elastic layer is effective in balancing warping forces on both surfaces of the fiber reinforced resin layer to avoid substantially apparent warping and avoid the possible peeling of the laminated product after adherence on a substrate. A backing layer may further be provided for improving the adherence with a substrate during application on the lowermost surface of the laminated product, i.e., on the surface of the fiber reinforced resin layer opposite to the surface on which the elastic layer is laminated when the second elastic layer is not provided, or on the surface of the second elastic layer opposite to the surface on which the fiber reinforced resin layer is laminated when the second elastic layer is provided. The backing layer thus provided can improve the adherence of the laminated product with the substrate during application.
The above and other objects, features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings which illustrate examples of the present invention.